Meanwhile, peel and slice your apples.
Preheat the oven to gas mark 3.
After an hour has passed, remove the pastry from the refrigerator. Cut the pastry in half (one half for the bottom of the pie and the other half for the top). It is often helpful to have one half slightly bigger and to use this half for the bottom of the pie. The bottom needs to be slightly bigger to cover the sides of the pie dish.
Roll the pastry out.
Assemble the bottom layer of pastry in the pie dish
Pour the apple mixture over the pie dish. Sprinkle the caster sugar and cinnamon over the apples.
Place the upper layer of pastry on top of the apple mixture, sealing the sides tightly with a knife or fork.
Brush the eggwash glaze over the pastry and pierce a few vents in the top of the pie using a fork.
Bake the pie for approximately 45 minutes until the pastry is golden brown
Dust with icing sugar before serving.
Serve with freshly whipped cream or ice cream.